The present invention generally relates to the construction of non-electric, turbine-powered train locomotives. More particularly, the present invention relates to the design and construction of an enclosure surrounding the turbine engine that powers a non-electric locomotive.
Considering the frequency with which many people travel in today""s modern world, and considering the time constraints that those people encounter in their daily lives, air travel has become a primary mode of transportation. Rail travel (or travel by train) has become a less attractive alternative because trains cannot compete with the speed of travel, and therefore the convenience of short travel time, that airplanes offer.
Accordingly, a need has developed for rail travel providers to consider alternative ways in which they can compete with air travel providers. One solution that presents itself is the development of trains that operate at higher than conventional speeds, for example, speeds from 125 to 150 miles per hour (m.p.h.) (and possibly even greater speeds up to or more than 165 m.p.h.). While this solution is simple, the application of this solution to the problem is not.
The dynamic forces exerted by the wheels of a locomotive on existing tracks are one of the most significant issues to be addressed before trains may be permitted to operate at high speeds, especially on North American railways. Conventional diesel-electric passenger locomotives (a common example of which is the xe2x80x9cF40xe2x80x9d locomotive, to which reference is made throughout) generally weigh around 260,000 lbs. In addition, they have high unsprung masses (about 8,540 lb./axle) due to the standard arrangement of the motors on the axles. (The xe2x80x9cunsprung weightxe2x80x9d refers to the weight of the components, especially the traction motors, which are mounted directly on the truck axle below the primary suspension. The high unsprung weight of the F40 locomotive results, at least in part, from the traction motors being mounted directly onto the axles.
At high speeds, the weight and unsprung mass of conventional diesel-electric locomotives exert significant dynamic forces on the rails. The dynamic forces, of which the unsprung weight is a significant contributing factor, are induced onto the tracks at locations where the locomotive crosses irregularities in the tracks, such as where the rails are welded or soldered to one another. The greater the dynamic forces exerted on the rails, the more rapidly the rails wear and the more frequently maintenance is required.
There are two solutions to this problem that are immediately apparent. First, the rails can be redesigned to withstand the dynamic forces exerted by conventional diesel-electric locomotives at high speeds. Second, the locomotives can be redesigned to minimize wear on the rails.
While technologically feasible, the first option is not financially attractive. Upgrading existing rails so that they can withstand the dynamic forces that a diesel-electric locomotive would exert at 125-150 m.p.h. requires that the rails be significantly redesigned or replaced entirely. This is prohibitively expensive. Therefore, engineers have focused on the second of the two solutions.
Since the weight and unsprung mass of locomotives are the primary contributing factors to the dynamic forces exerted on the rails, engineers have focused on designing lighter locomotives that have a lower unsprung mass. When considering this option, two choices are possible: (1) an electric locomotive, i.e., a locomotive that draws power from an electrified rail or overhead cable, or (2) a non-electric locomotive, i.e., a locomotive that generates it own power (without an electrified rail or overhead cable). The first option is hereinafter referred to as the xe2x80x9call-electricxe2x80x9d option.
It should be noted that electric and non-electric locomotives both may use electrical energy to one degree or another, i.e., to power the electric traction motors for propulsion. The distinction here is that a non-electric locomotive generates its own electrical power while an electric locomotive relies on an external power source, such as an electrified rail or overhead cable, for electrical energy. In other words, the appellation xe2x80x9cnon-electric locomotivexe2x80x9d is not meant to convey that the locomotive operates without electrical energy of any kind.
The all-electric option offers potentially the greatest reduction in the weight of the locomotive because the locomotive does not need to carry its own power generator(s). Instead, the locomotive receives its power from an external source. While this option potentially leads to the lightest locomotive design, it requires a significant investment because existing rails must be electrified (by providing a power rail or electrified overhead cable). It has been estimated that the cost of electrifying a single mile of track could cost between $3 and $5 million dollars. This is cost prohibitive in most geographic areas because there is insufficient passenger ridership to justify the expenditure.
Therefore, from the options listed, the most viable proposition for a high-speed train locomotive for use on as many railways as possible is a non-electric locomotive with a weight and unsprung mass that is lower than the conventional diesel-electric locomotive. One way to accomplish this objective is to provide a locomotive with a low-weight power generator, such as a turbine engine.
Two primary characteristics of turbine engines, however, offer significant challenges to their use in locomotives. First, turbine engines generate a considerable amount of heat. This requires powerful cooling systems to remove the heat from the engine while it is running. Second, turbine engines consume a large volume of air during operation. This requires the incorporation of systems in the locomotive design that accommodate this need.
Despite these engineering challenges, turbine engines are significantly lighter (in weight) than the internal combustion engines that are conventionally used. The reduced weight of turbine engines as compared to conventional (i.e., diesel) engines offers a compelling reason for engineers to overcome the challenges associated with reliance on turbine-generated power in locomotive applications.
The use of turbine-power (of one sort or another) has been proposed for locomotives in the past. For example, U.S. Pat. No. 2,533,866 describes an electric locomotive with a coal-fired, gas-turbine power plant to generate power by using the exhaust gases produced when coal is burned. The turbine is connected to electrical generators that are, in turn connected to the driving motors on the locomotive.
U.S. Pat. No. 2,637,277 describes a specific construction for a locomotive with a gas turbine power plant. Specifically, the patent describes how irregularities in the roadbed over which a locomotive travels can generate forces that longitudinally twist the frame of the locomotive. This twisting can be transmitted to the rotary units on the locomotive and cause the shafts of the units that are connected together to become misaligned. The patent is directed to a support structure that renders harmless any longitudinal twisting of the locomotive frame as it passes over an uneven roadbed. The locomotive described includes a gas turbine power plant connected to an electric generator that supplies power to a plurality of traction motors that drive the locomotive.
U.S. Pat. No. 3,862,604 describes a locomotive engine compartment for a turbine-powered locomotive. Specifically, the patent describes grouping the power components of the locomotive in a compact arrangement within a room that is both thermally and acoustically insulated. Being insulated, the room can be located a fairly short distance from passenger and baggage compartments. The room is divided into two parts: (1) a first part called the xe2x80x9cstabilization chamber,xe2x80x9d in which, after passing through the scoop, the air expands before entering the air filter; and (2) a second part, called the xe2x80x9cturbine compartment,xe2x80x9d which accommodates the main and auxiliary turbines and exhaust release.
U.S. Pat. No. 4,087,961 describes a fuel control system for a gas turbine engine operated on gaseous fuel. Specifically, the fuel control system is designed to provide a limit switch that prevents overheating of the turbine engine. When additional power is demanded, the governor that controls the flow of fuel to the turbine may open fully and remain opened for extended periods of time. To prevent overheating of the engine, a system is provided that measures the compressor discharge pressure and prevents the fuel metering valve from opening beyond a certain position even though the governor may call for more fuel.
Finally, U.S. Pat. No. 5,129,328 describes a locomotive incorporating a gas turbine engine that uses natural gas as its fuel. The turbine is connected directly to an alternator without a gearbox. To fuel the locomotive, a number of separate cylindrical containers are provided on the locomotive frame to contain the natural gas fuel at a pressure of about 3,000 pounds per square inch.
While each of these patents address certain issues associated with the use of turbine power for locomotives, the combination of elements, as described below, is entirely new.
The present invention offers a new and unique approach to the use of turbine engines as the power source for train locomotives.
Specifically, it is an object of the present invention to offer a unique construction for the enclosure for the turbine engine that dissipates heat generated by the engine during operation.
It is another object of the present invention to provide a unique construction for the enclosure assembly that accommodates the large air intake required by the turbine engine without the need for ducting.
In addition, it is an object of the present invention to provide a diesel-fueled turbine-powered locomotive that exerts smaller dynamic forces on the rails over which it travels than a conventional diesel-electric locomotive, such as the F40 locomotive.